1. Field of the Invention
The present invention relates to a data transmitter, a data receiver, a data communication system, and a data communication method, capable of achieving smooth two-way communications between a connected external device and a destination or a sender in real time.
2. Description of the Prior Art
In the prior art, as an interface for use in a commonly used data communication system, there have been known D2B (Audio, video and audiovisual systems Domestic Digital Bus: CIE/IEC 1030) used upon transmitting digital audio data, digital audio interface (Digital audio interface: CIE/IEC 958), etc.
In FIGS. 1 and 2, a frame format and a subframe format of a signal in a digital audio interface in which blocks, frames, and subframes are arranged in a hierarchical manner is shown respectively. As shown in FIG. 2, respective items, i.e., a synchronizing preamble, an audio auxiliary, an audio sample word, a validity flag, a user data, a channel status, and a parity bit are allocated to a subframe which is placed at a lowermost layer. One frame of 64 bit is constituted by combining a pair of 32 bit subframe which are allocated to right and left two channels respectively and thus one block is composed of successive 192 frames.
Meanwhile, at the time when digital audio data are transferred from a certain sender to a particular destination, commonly header information including a sender, a destination, etc. are allocated to a group of digital audio data as a transferred object in a sender.
Upon allocating the header information to the digital audio data having the above data format, for example, header information are allocated to a user data area which is used freely by the user, etc. In this manner, the digital audio data can be transmitted firmly to a predetermined destination.
However, according to a conventional header information allocation method as described above, there have been problems to be overcome such that a large capacity memory has to be prepared as a buffer memory, in which the digital data as a transfer object are stored temporarily, in the sender and that the digital data cannot be transferred to the destination in real time because of a waiting time required for data accumulation.
In more detail, in the header information allocating method in the prior art, the header information are allocated over plural blocks because a considerable number of bits are required for allocating the header information. For this reason, the digital data ranging over plural blocks must be stored in the buffer memory until interpretation of the header information allocated over plural blocks has been completed in the sender. As a consequence, in the prior art, a large capacity memory has to be prepared as the buffer memory and the digital data cannot be transferred to the destination in real time due to the waiting time required for data accumulation.